Testing for pressure loss

[JSchuricht]

So yesterday I was getting up to speed, shifted into OD normally but I noticed the converter was unlocked, looked down and sure enough the OD light was flashing. Continued to the next light and pulled into the parking lot at my destination, put her in reverse to park and it felt like the TC locked up. I hit the brake and she stalled. I finished my shift and drove 4 miles back home without any issue. Today I pulled the codes, only thing I found is P0741 which it TC clutch performance or stuck off. I am leaning towards low line pressure from what I have read due to the stall in reverse and a slight delay going from drive to reverse. I just ordered a

pressure test kit

pressure test kit

, what's the best way to narrow down the cause of the pressure loss, assuming that's what it is.

[RadarRider]

Originally Posted by JSchuricht

So yesterday I was getting up to speed, shifted into OD normally but I noticed the converter was unlocked, looked down and sure enough the OD light was flashing. Continued to the next light and pulled into the parking lot at my destination, put her in reverse to park and it felt like the TC locked up. I hit the brake and she stalled. I finished my shift and drove 4 miles back home without any issue. Today I pulled the codes, only thing I found is P0741 which it TC clutch performance or stuck off. I am leaning towards low line pressure from what I have read due to the stall in reverse and a slight delay going from drive to reverse. I just ordered a pressure test kit, what's the best way to narrow down the cause of the pressure loss, assuming that's what it is.

More than likely, you ARE looking at a pressure problem. If anything, your pump might be the source of the problem if your trans hasn't been serviced regularly. Try the pressure test & see what you get & let us know about what you find.

[JSchuricht]

Thanks, at least there is some hope I am on the right track. The transmission was rebuilt about 10k ago and hasn't been serviced since. I was just going through the receipt and there is no mention of a pump so it's likely the original. Is there any way to isolate the pump and just test it for pressure?

[RadarRider]

Originally Posted by JSchuricht

Thanks, at least there is some hope I am on the right track. The transmission was rebuilt about 10k ago and hasn't been serviced since. I was just going through the receipt and there is no mention of a pump so it's likely the original. Is there any way to isolate the pump and just test it for pressure?

Yes. If the transmission's been rebuilt, it's unlikely they replaced the pump. Believe it or not, they're not very prone to failure, but certain upgrades you can get for your trans require you to get an upgraded one. Let me get back to you on isolating the pump. There is a test you can perform with the pressure gauge, but it's been a while since I've done any pressure testing. For the past 2yrs, I've been stuck rebuilding them only.

[JSchuricht]

Well after my gauges got redelivered to the correct address I did a bit of testing. At idle P=90 psi, r=127 psi, n=90 psi, d=92 psi, 2=90 psi, 1=105 psi. 1st makes a weird sound for a second and spikes between 130-180 psi before settling on 105 psi. I am fairly sure it's not the pump now... I did what I should have done in the first place and actually checked the transmission fluid, with only 10k on it I hadn't been paying much attention to it. The fluid is a milky grey, I don't know how water could get in but that's what it looks like. I'm going to flush everything as best I can and hope for the best.

[RadarRider]

Yeah, I don't believe it's your pump either. By the sound of things, your problem may lie in the valve body. If there's any kind of debris, build up, or even water inside the valve body, you'll get poor trans operation. Your valve body's responsible for sending fluid to your reverse, forward gears, & neutral to the correct valve/drum inside your trans. Do you have your own facility to remove your trans?

[JSchuricht]

I wish I had a garage, I just have a carport but I do have the tools to pull the trans if necessary. The valve body shouldn't be too hard to pull and clean with the trans still mounted. I was thinking of getting a new valve body but somehow I don't think putting more money into this trans will pay off at this point.

Kinda pissed off at this point. Spent $3849.81 getting this trans rebuilt just a few hours from John Woods but I was still in the Navy and had limited time to get back to base. Looking through my receipt, I was only charged for 15 quarts of ATF so they probably didn't flush everything. To rub it in a bit more, I have a 5 year prorated warranty but it's a 1100 mile drive.

[RadarRider]

I wish I had a garage, I just have a carport but I do have the tools to pull the trans if necessary. The valve body shouldn't be too hard to pull and clean with the trans still mounted. I was thinking of getting a new valve body but somehow I don't think putting more money into this trans will pay off at this point.

Kinda pissed off at this point. Spent $3849.81 getting this trans rebuilt just a few hours from John Woods but I was still in the Navy and had limited time to get back to base. Looking through my receipt, I was only charged for 15 quarts of ATF so they probably didn't flush everything. To rub it in a bit more, I have a 5 year prorated warranty but it's a 1100 mile drive.

No, you don't need to remove the trans for the VB, but I was just wondering if you could if you ever wanted to disassemble it. After you drop your trans, believe it or not, they're easy to work on. I rebuild 4R100/E4ODs & they're not complicated. Most areas of these trans' are easy to intermediate for mechanical skill level. Full rebuilds really require an expert, but if you can use micrometers & feeler gauges & know where to use them in certain areas, someone with intermediate skill could probably rebuild these trans' if they went real slow, paid close attention to detail, & had patience.

Anyway, before I write another book- back to removing the trans. If you can drop your trans, & have a free weekend, you could clean out the entire transmission. I know this sounds off the handle, but if the condition of the ATF that comes out of the pan is showing you there's a lot of grit or even water in the system, it'd take you a minimum of a day(if your current set up allows) & at least you & another able person to drop the trans, take it apart, steam/pressure wash the trans body, clean out the valve body, accumulator, shift solenoids, replace all gaskets & seals, reassemble & reinstall the trans.

Once again, I know it's overkill, but when it came to experiencing how some trans shops operate, I'd rather do it myself. You'll learn a lot & save yourself countless $$$ & you'll be able to fully modify your trans if you ever wanted to. They're so easy, I wish more people would give it a shot.

[JSchuricht]

Not sure I really want to dig that far into the transmission yet. 20nm processors I can handle, transmissions are still a bit foreign to me. Perhaps if a flush doesn't work I will try puling it apart and cleaning it.

[JSchuricht]

It's looking worse than I expected. Tons of metal flakes, I had already cleaned the plug before the pic. The filter was holding back a bunch of fluid, I had expected some of it to drain back through the filter. Then the fun stuff, found one stripped bolt hole and found most of my cooler lines had just started to leak at the joints where the hose meets metal.